Tunneling spectra of submicron Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8+\hat{I}´}$ intrinsic Josephson junctions: evolution from superconducting gap to pseudogap

Abstract

Tunneling spectra of near optimally doped, submicron Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8+\hat{I}´}$ intrinsic Josephson junctions are presented, and examined in the region where the superconducting gap evolves into pseudogap. The spectra are analyzed using a self-energy model, proposed by Norman {\it et al.}, in which both quasiparticle scattering rate $\hat{I}“$ and pair decay rate $\hat{I}{“}_{\hat{I}}”$ are considered. The density of states derived from the model has the familiar Dynes' form with a simple replacement of $\hat{I}“$ by ${\hat{I}}_{+}^3$ = ($\hat{I}“$ + $\hat{I}{“}_{\hat{I}}”$)/2. The ${\hat{I}}_{+}^3$ parameter obtained from fitting the experimental spectra shows a roughly linear temperature dependence, which puts a strong constraint on the relation between $\hat{I}“$ and $\hat{I}{“}_{\hat{I}}”$. We discuss and compare the Fermi arc behavior in the pseudogap phase from the tunneling and angle-resolved photoemission spectroscopy experiments. Our results indicate an excellent agreement between the two experiments, which is in favor of the precursor pairing view of the pseudogap.

7 pages, 6 figures